Plants acquire nitrogen, a vital element for protein synthesis, through various means, primarily from the soil. They don't directly absorb atmospheric nitrogen.
Methods of Nitrogen Acquisition by Plants
Plants obtain nitrogen from the soil in two primary forms:
- Inorganic Salts: Plants absorb nitrogen as inorganic salts, specifically nitrates or nitrites, directly from the soil. This is a common way plants access the required nitrogen.
- Organic Compounds: Some plants get nitrogen in the form of organic compounds. These organic nitrogen compounds are created by bacteria. These bacteria use atmospheric nitrogen to synthesize these organic compounds, making it accessible to plants in the soil.
The Nitrogen Cycle
The process through which nitrogen is made available to plants involves several stages known as the nitrogen cycle:
- Nitrogen Fixation: Bacteria convert atmospheric nitrogen into usable forms like ammonia.
- Nitrification: Other bacteria convert ammonia into nitrites and then into nitrates.
- Assimilation: Plants absorb nitrates from the soil.
- Ammonification: Organic nitrogen from dead plants and animals gets converted into ammonia.
- Denitrification: Nitrates get converted back into atmospheric nitrogen under certain conditions.
Summary
In short, plants cannot directly use atmospheric nitrogen. They get their nitrogen from the soil as either inorganic salts such as nitrates and nitrites or as organic compounds, which are made available by the action of bacteria using atmospheric nitrogen.
| Source of Nitrogen | Form Absorbed | Description |
|---|---|---|
| Soil | Nitrates (NO3-) and Nitrites (NO2-) | Inorganic salts directly absorbed by the plant's roots. |
| Soil (via bacteria) | Organic compounds formed by bacteria using atmospheric nitrogen. | Bacteria convert atmospheric nitrogen into forms that can be used by plants, like organic compounds, which are then absorbed by the roots. |
